1. Field of the Invention
The invention relates to a paper cutter for cutting to-be-cut paper placed in a correct position on a base, and more specifically, the invention relates to a paper cutter capable of securely and steadily press-holding to-be-cut paper onto a base.
2. Description of the Related Art
In a conventionally used paper cutter, a paper holding member supported on a base to be vertically movable is provided. To-be-cut paper positioned and placed on the base is press-held by the paper holding member, a slider is moved along the paper holding member, and the to-be-cut paper is cut by a rotary blade attached to the slider.
As a paper holder unit in a paper cutter of the type described above, for example, there is a paper holder unit in accordance with Japanese Patent No. 3113953 owned by the present applicant. The paper holder unit in the paper cutter according to the above-referenced patent is constructed as described hereunder. There are disposed two operation rods, namely first and second operation rods, which are formed of flat parallelogram plate materials each having slanted faces being parallel with each other at both side end portions in a longitudinal direction of the base. The two operation rods, namely the first and second operation rods, are arranged in parallel with each other on the base and are supported thereon to be horizontally movable. These operation rods are disposed such that the slanted faces in corresponding end portions of the respective adjacent operation rods are disposed in vertically opposite slanted directions. In addition, first and second movable members are disposed in opposition to the vertically opposite slanted faces.
The first and second movable members are movably supported in a vertical direction at both side end portions of the longitudinal direction of the base. A paper holding member is bridged between the first and second movable members, whereby both side end portions of the paper holding member in a longitudinal direction are supported. The first and second movable members are constantly urged upward by elastic forces of coiled springs, and are disposed to a predetermined height. A space in which the to-be-cut paper is to be inserted is formed between the paper holding member and the base. In the paper holding member, a slider to which a rotary blade is attached is slidably provided, and is positioned to the cutting position of the to-be-cut paper in accordance with an edge of the paper holding member. A side face of the rotary blade of the slider rotates in contact with the edge of the paper holding member whereby to cut the to-be-cut paper.
In the first movable member, there are provided adjacent to each other an abutment portion (corner portion) for abutting on the upward slanted face formed in the first operation rod, and an abutment portion (bottom edge of a horizontally recessed opening) for abutting on the downward slanted face formed in the second operation rod. In the second movable member, in the disposition relationship opposite to the above, there are adjacently provided an abutment portion (bottom edge of a horizontally recessed opening) for abutting on the downward slanted face formed in the first operation rod, and an abutment portion (corner portion) for abutting on the upward slanted face formed in the second operation rod.
In the conventional paper holder unit, in the event that the slider including the rotary blade is operated to slide while the paper holding member is depressed, when the paper holding member is depressed by the slider in resistance with the elastic force of the first movable member, the abutment portion (corner portion) of the first movable member depresses the upward slanted face of the first operation rod. At this event, according to wedge actions by the upward slanted face of the first operation rod and the abutment portion (corner portion) of the first movable member, the first operation rod performs a horizontal movement along the base. By the horizontal movement of the first operation rod, a tip of the downward slanted face formed at the other end of the first operation rod is pushed into the abutment portion (bottom edge of the horizontally recessed opening) of the second movable member. Then, the second movable member is pulled down according to wedge actions by the downward slanted face formed at the other end portion of the first operation rod and the abutment portion (bottom edge of the horizontally recessed opening) of the second movable member.
When the second movable member is pulled down, the abutment portion (corner portion) of the second movable member formed adjacent to the abutment portion (bottom edge of the horizontally recessed opening) of the second movable member abuts on the upward slanted face of the second operation rod, whereby the second operation rod performs a horizontal movement in a direction opposite to the first operation rod. When the second movable member moves in the horizontal direction, a tip of the downward slanted face formed at the other end of the second operation rod is pushed into the abutment portion (bottom edge of the horizontally recessed opening) of the first movable member. Then, the first movable member is pulled down according to wedge actions by the downward slanted face of the second operation rod and the abutment portion (bottom edge of the horizontally recessed opening) of the first movable member.
As described above, the slanted faces formed in the both end portions of the first and second operation rods in the longitudinal direction are disposed parallel with each other with respect to the same operation rods, and the slanted faces of the adjacent operation rods are slanted in opposite directions alternately. As such, when the first and second operation rods and the first and second movable members move in cooperation with one another, the first movable member on the one side is vertically moved, whereby also the second movable member on the other side is enabled to vertically move in the same direction as the first movable member.
Thereby, when the paper holding member is depressed by the slider at an arbitrary position of a rail, the first and second movable members are moved downward, whereby the paper holding member is moved downward while the parallel state with respect to the base is being constantly maintained. When the depressing force of the paper holding member imparted by the slider is relieved, the paper holding member is ascended so as to be detached from the base by the forces of the coiled springs disposed between the first and second movable members and the base.
Accordingly, even when cutting a stack of many to-be-cut paper sheets, misalignment of the to-be-cut paper is prevented and concurrently, alignment of the cutting position can easily be performed, consequently enabling cutting to be performed into accurate sizes.
As described above, according to the conventionally used paper holder unit as disclosed in the specification of the above-referenced patent, the paper holding member is depressed by the slider and is concurrently caused to slide. Thereby, at each slide position of the slider, the first and second operation rods can be moved in parallel in a reversed direction, respectively, via the paper holding member, and the first and second movable members can be descended in cooperation with the horizontal movement of the first and second operation rods. According to the descendent movement of the first and second movable members, the paper holding member supported between the first and second movable members can be moved downward while the parallel state is being maintained, consequently enabling the paper holding member to press-hold the to-be-cut paper substantially at a uniform state.
However, the force to descend the first movable member when cutting by the slider is initiated causes the first operation rod to perform the horizontal movement. Concurrently, the force works to descend the second movable member, and then works as a force causing the second operation rod to perform the horizontal movement. As such, a problem arises that an excessive force should be performed before the horizontal movement of the second operation rod.
Further, in terms of the structures, the first and second operation rods slide in a surface-contact state where the operation rods are in close contact with the abutment surfaces of the first and second movable members. As such, the sliding resistance due to the surface contact is increased, and nonuniformity in the operation forces to the first and second operation rods is facilitated to occur, thereby making it difficult to secure smooth sliding of the first and second operation rods. Particularly, with first and second operation rods formed of a material having flexibility, distortion in a horizontal direction is caused in the first and second operation rods during operation, thereby offering the problem of disabling obtaining high sliding performance with respect to the base.
In addition, the angles at which the abutment surfaces of the first and second movable members and the slanted faces of the first and second operation rods engage with one another should be appropriately set. Therefore, the shapes, structures, patterns, and the like of the first and second movable members, first and second operation rods, and the like should be strictly set, and high dimensional precisions for products become necessary. Further problems take place in that highly-level tuning should be performed for setting/alignment and the like between the individual members such as the first and second movable members and the first and second operation rods, and strict inspection should be carried out to solve such the problems. Consequently, increases in costs, such as facility costs and manufacturing costs are introduced, and strict quality control is required.
When sufficient precisions cannot be obtained in regard to set dimensions, assembly tuning, and the like, the frictional resistance on the slanted faces are increased, also the nonuniformity in the slide resistances of the first and second operation rods is increased. Thus, a force applied to the paper holding member from the slider are disabled to work as a force for intensively depressing both the first and second movable members. Consequently, it becomes to difficult to descend both the first and second movable members at the same time, whereby the paper holding member cannot be uniformly press-held with respect to the to-be-cut paper, and an incident occurs in which the paper holding member partly floats above the base.
In the meantime, it can be contemplated that in order to steadily press-hold the to-be-cut paper placed on the base, a robust paper holding member is used, and the rigidities of the first and second operation rods are enhanced to secure higher durabilities thereof. However, when the construction of this type is employed, while the rigidities, durabilities, and the like of the first and second operation rods can be secured, special materials should be used to form the first and second operation rods. Consequently, material costs are increased, thereby introducing the problem of impairing low-cost production.
The present invention is made to solve the above-described problems. Accordingly, an object of the invention is to provide a paper cutter including a paper-holding function, in which the structure is simple and inexpensive, a paper-holding function maintaining an ensuredly steady and excellent state is secured, quality improvement and cost reduction can be implemented, and a press-holding force for paper onto a base is substantially uniformed and can be intensified even when an arbitrary position of a paper holding member is depressed by a slider.